Humans are still evolving

A defining characteristic of ideologies is an implicit or explicit theory of human nature. For example, modern libertarians like Ayn Rand and Murray Rothbard derived bold normative conclusions from the fact that humans are endowed with reason. In such attempts, an abstract theory of human nature is made to do more work than it can possibly do; provide all humans with a set of normative guidelines for social interaction. The failure of such “rationalist” approaches to draw ideological conclusions from human nature does not mean that knowledge about human nature has no role to play in social philosophy or public policy at all. Absent deriving grandiose categorical imperatives, knowledge of human nature can provide us with knowledge about the limits of human malleability or the feasibility of specific public policy proposals. To be able to play this role, however, it needs to satisfy at least two criteria; it needs to be based on experimental evidence and it should be situated in an evolutionary context.

Many writers about human nature are aware of the social sensitivities surrounding this topic. As a consequence, most contemporary books that aim to provide a theory of human nature need to walk a fine line between providing a plausible evidence-based perspective and avoiding presenting an account of human nature with controversial social-political implications. What makes many books about human nature not entirely persuasive is the implicit premise that humans have stopped evolving since our descendents left Africa around 50,000 years ago. Stephen Jay Gould was quite explicit about this when he wrote that “there’s been no biological change in humans in 40,000 or 50,000 years. Everything we call culture and civilization we’ve built with the same body and brain.” One problem with these accounts is that genetic evidence keeps accumulating that humans not only kept evolving over the last 50,000 years, but that the pace might even have accelerated after the start of agriculture and modern civilization. Two books about human nature that explicitly depart from the view that humanity has not experienced meaningful genetic change over the last 50,000 years are Nicholas Wade’s Before the Dawn: Recovering the Lost History of Our Ancestors (2006) and Gregory Cochran and Henry Harpending’s The 10,000 Year Explosion: How Civilization Accelerated Human Evolution (2009). Before the Dawn provides a general evolutionary account of human origins and The 10,000 Year Explosion specifically aims to provide theoretical arguments and empirical evidence for recent genetic change and its implications. As such, The 10,000 Year Explosion can be read as a sustained, detailed treatment of one of the themes in Before the Dawn and constitutes a major contribution to the resuscitated field of “biohistory.”

Since both authors reject the theory that 50,000 years is too short for genetic changes to occur, both books discuss emerging evidence that diverging populations responded with different genetic adaptations to the environments they encountered. Nicholas Wade devotes a whole chapter to the view that the concept of race may have been abandoned without good scientific reason and that this concept can do meaningful work in population genetics, history, medicine, and forensic science. Such a perspective makes evolutionary scientist Steven Pinker uncomfortable. In an interview in New Scientist magazine he admits, “People, including me, would rather believe that significant human biological evolution stopped between 50,000 and 100,000 years ago, before the races diverged, which would ensure that racial and ethnic groups are biologically equivalent.”

Commenting on Jared Diamond’s (mostly) environmentalist perspective, Wade writes, “If New Guineans adapted genetically by developing the intellectual skills to survive in their particular environment, as Diamond says is the case, why should not other populations have done exactly the same?” Both books argue that this is exactly what has happened, and give a number of examples. In particular, they discuss the hypothesis that the unique history of the Ashkenazi Jews triggered genetic adaptations that make them excel in cognitive tasks. In addition, Cochran and Harpending do not just argue that race is more than skin-deep, but also explain why similar traits can reflect different genetic adaptations. In the closing chapter they write, “If researchers in the human sciences continue to ignore the fact of ongoing natural selection, they will have thrown away the key to many important problems, turning puzzles into mysteries.”

Nicolas Wade also expresses concern over the tendency of many post-war archeologists and anthropologists to play down or even deny the prevalence of warfare (and other cruel practices) in primitive and pre-State societies. This theme has been treated in detail by Robert B. Edgerton in his book Sick Societies: Challenging the Myth of Primitive Harmony, and, more recently, in Steven Pinker’s new book, The Better Angels of our Nature. Such wishful, or anti-Western, thinking not only obscures the progress that has been made in many modern societies, it also prevents scholars from properly assessing the role that warfare and competition has played in shaping human nature. In fact, in his book The Dawn Warriors: Man’s Evolution Toward Peace, Robert Sidney Bigelow dispels the myth of primitive harmony and proposes that continuous warfare gave rise to increased in-group cooperation and increased brain size.

If natural selection is still at work in humans, an obvious question is where we are heading, or could be heading, if we allow for the possibility that humans may soon have real control over their genetic destiny. This topic is treated in a very interesting manner in the last chapter of Before the Dawn. Nicholas Wade discusses the current trend that the rich and more intelligent tend to have fewer children but without reaching a firm conclusion whether this will produce natural selection to act against genes that promote intelligence. Even if such a scenario would occur it might be offset by new technologies that allow genetic human enhancement. Such developments could even produce new post-human species who are not capable of breeding with modern humans. “Our previous reaction to kindred species was to exterminate them, but we have mellowed a lot in the last 50,000 years,” writes Wade. Whether un-enhanced humans will survive in the long run is an open question.

An extensive 5-part interview with Gregory Cochran is available here:
Part One

Part Two
Part Three
Part Four
Part Five

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